如何合计3个select语句计数？

gdx19jrr 于 2021-06-21 发布在 Mysql

关注(0)|答案(3)|浏览(432)

我有三个select语句如下，我想总结一下记录的总数。我该怎么做？

SELECT COUNT(*) AS Number FROM tableA where user_id = 5   //Total 5 records
SELECT COUNT(*) AS Number FROM tableB where user_id = 5   //Total 6 records
SELECT COUNT(*) AS Number FROM tableC where user_id = 5   //Total 1 records

所以返回结果是12。

sql mysql select

来源：https://stackoverflow.com/questions/50773215/how-can-i-total-up-3-select-statement-count

3条答案

按热度按时间

ecfdbz9o1#

你可以申请 count(*) 结果是 union all :

SELECT COUNT(*)
FROM   (SELECT user_id FROM tablea
        UNION ALL
        SELECT user_id FROM tableb
        UNION ALL
        SELECT user_id FROM tablec) t
WHERE  user_id = 5

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6vl6ewon2#

select ( select count(*) from tableA where user_id = 5 )
     + ( select count(*) from tableB where user_id = 5 ) 
     + ( select count(*) from tableC where user_id = 5 ) 
     as total_rows
from dual

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lawou6xi3#

我认为这应该起作用：

SELECT SUM(Number)
FROM (
    SELECT COUNT(*) AS Number FROM tableA where user_id = 5
    UNION ALL
    SELECT COUNT(*) AS Number FROM tableB where user_id = 5
    UNION ALL
    SELECT COUNT(*) AS Number FROM tableC where user_id = 5
)

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如何合计3个select语句计数？

3条答案

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